The Foreign Secretary William Hague has called for politicians in Iraq to put aside sectarian differences to confront the "existential" threat from Isis led Sunni fighters.
Mr Hague is due to meet with Shia prime minister Nouri al-Maliki and other key figures. Arriving in Baghdad he said:
The single most important factor that will determine whether or not Iraq overcomes this challenge is political unity.
As a friend of Iraq, the UK believes the urgent priority must be to form an inclusive government that can command the support of all Iraqi people and work to stop Isis in its tracks.
Isis is a brutal terrorist group that is alien to this country, to the Middle East, and to the Islamic faith. It is a mortal threat to the stability and territorial integrity of Iraq, but the danger does not stop here: Isis poses a direct threat to other countries in this region.